The present invention relates generally to end closures for metal containers and more particularly to can end closures which have improved sealing means while retaining easy opening features.
There has been a continuing demand for a lid construction for such cans which may be opened without the use of separate opening devices. One such construction, generally termed the "pull-tab," embodies a scored gate outline in the surface of the can lid and a supplemental lever attached to the gate portion to facilitate breaking the gate portion along the scored outline and lifting it from the can end. However, this type construction has several inherent disadvantages. One such disadvantage relates to the possibility of minor injuries resulting from contact with the edges of the opening or of the discarded pull-tab. A further disadvantage of such construction relates to ecology, and involves the rather prevalent indifference as to the proper disposal of the detached tabs, causing complaints of injury and litter and promoting legislation directed at the banning of such containers.
Another type of can end construction which has been proposed in recent years is the push-in tab type. Examples of can end construction of this type can be found disclosed in U.S. Pat. No. 3,227,304 to Asbury, granted Jan. 4, 1966, U.S. Pat. No. 3,362,569, to Geiger, granted Jan. 9, 1968, U.S. Pat. No. 3,334,775, to Klein et al., granted Aug. 8, 1967, and U.S. Pat. No. 3,759,206, Dalli et al., granted Sept. 18, 1973.
The Asbury patent discloses a can opening arrangement which embodies a can end having score lines which may define two equal-size, inwardly-displaceable tab portions or scored regions in the can end.
The Geiger patent is somewhat similar to the Asbury patent, and discloses a pair of substantially identical raised tabs which are depressable into the can body. Unlike the Asbury patent, however, Geiger does not utilize a score mark to define tab portions and to produce a weakening in the can end; rather, the patent comprehends partial shearing of the can end to offset and weaken the metal defining the tab portions. The partial shear leaves a residual wall section which is intended to break when the tab portion is depressed.
The Klein et al. patent discloses a push-in opening feature similar to the Asbury and Geiger patents in that a score mark is utilized for breaking the tab portion or panel away from the can end. A feature in the Klein et al. patent differing from the Asbury and Geiger patents is that the tab panel is formed integrally with the can end by underfolding the panel 180.degree. outwardly and about the opening, to form a narrow spacer strip at the underside of the can end about the edge of the opening, the score mark being located at the underfold and away from the opening. Thus, the possibility of minor injury resulting from the edge of the opening is eliminated by the Klein et al. construction.
Finally, the Dalli et al. patent describes a can end closure from which portions are preferably partially severed to form two similarly dimensioned and configured openings, and to provide corresponding closure members.
Henchert et al., in U.S. Pat. No. 3,251,515, discloses a container closure provided with two openings of different sizes, which are closed by slugs stamped from the end panel and secured to a peelable strip or tape.
A hybrid sort of closure arrangement is taught in Dunn et al. U.S. Pat. No. 3,441,169, consisting of a relatively small, inwardly-displaceable vent area, and a rather conventional removable tear strip.
It is, therefore, a primary object of the present invention to provide an improved easy open can end closure with new and improved sealing means and which eliminates in whole or in part the disadvantages inherent in the can end closures discussed above.
More specifically, it is an object of the invention to provide novel sealing means for a can end closure having facile opening features.